Thursday, February 18, 2010

SCIENTISTS FIND QUANTUM MECHANICS AT WORK IN PHOTOSYNTHESIS

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A team of University of Toronto chemists have made a major contribution to the emerging field of quantum biology, observing quantum mechanics at work in photosynthesis in marine algae.

"There's been a lot of excitement and speculation that nature may be using quantum mechanical practices," says chemistry professor Greg Scholes, lead author of a new study published this week in Nature. "Our latest experiments show that normally functioning biological systems have the capacity to use quantum mechanics in order to optimize a process as essential to their survival as photosynthesis."

Special proteins called light-harvesting complexes are used in photosynthesis to capture sunlight and funnel its energy to nature's solar cells – other proteins known as reaction centres. Scholes and his colleagues isolated light-harvesting complexes from two different species of marine algae and studied their function under natural temperature conditions using a sophisticated laser experiment known as two-dimensional electronic spectroscopy.

"We stimulated the proteins with femtosecond laser pulses to mimic the absorption of sunlight," explains Scholes. "This enabled us to monitor the subsequent processes, including the movement of energy between special molecules bound in the protein, against a stop-clock. We were astonished to find clear evidence of long-lived quantum mechanical states involved in moving the energy. Our result suggests that the energy of absorbed light resides in two places at once – a quantum superposition state, or coherence – and such a state lies at the heart of quantum mechanical theory."

"This and other recent discoveries have captured the attention of researchers for several reasons," says Scholes. "First, it means that quantum mechanical probability laws can prevail over the classical laws of kinetics in this complex biological system, even at normal temperatures. The energy can thereby flow efficiently by—counter intuitively—traversing several alternative paths through the antenna proteins simultaneously. It also raises some other potentially fascinating questions, such as, have these organisms developed quantum-mechanical strategies for light-harvesting to gain an evolutionary advantage? It suggests that algae knew about quantum mechanics nearly two billion years before humans," says Scholes.

University of Toronto

NEW WAY TO LOSE FAT, KEEP THE LEAN

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Researchers reporting in the February 3rd issue of Cell Metabolism may have a new way to trick the body into consuming more energy. The target in this case is an enzyme that indirectly controls the activity of what the researchers refer to as the "energy master switch." It boils down to this: When you give mice a chemical that blocks the function of the enzyme known as Fyn kinase, they almost immediately begin burning more fat.

"When there is an imbalance between what we eat and what we burn," the outcome is obesity, said Claire Bastie of the Albert Einstein College of Medicine. "And the problem of obesity is not going away. This is a new mechanism to help the body to burn extra energy."

Bastie's team earlier showed that mice lacking Fyn kinase altogether burn more fatty acids and expend more energy to become leaner. They also showed other metabolic improvements, including increased insulin sensitivity. Those effects were the result of higher levels of the master energy switch AMPK in their fat and muscle tissue.

Those findings suggested that the enzyme might offer a useful target for a new kind of weight loss drug. Now, the researchers add support for that idea by showing that chemical inhibition of Fyn kinase with an experimental drug known only as SU6656 does have considerable metabolic benefits for mice. Ultimately, the animals appear to become increasingly fit as they lose fat and keep the lean.

The researchers further detailed exactly how the Fyn kinase works its magic. It acts on another component of the energy pathway, which leads to a change in AMPK levels.

Bastie said that SU6656 itself isn't an ideal drug candidate for clinical trials of the approach in humans. That's because Fyn kinase and AMPK both have effects in the brain as well as in fat and muscle. Scientists would need a drug that hits those molecular players only where you wanted it to. "Our next goal is to design something extremely specific to muscle and adipose," Bastie said.

She said she wants to find out what Fyn kinase and AMPK are doing in the brain, where she suspects they may play some role in appetite control. She also wants to find out what normally controls Fyn kinase levels, noting that it may be a fatty acid or some other nutrient.

Cell Press

CAN BLOCKING A FROWN KEEP BAD FEELINGS AT BAY?

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Your facial expression may tell the world what you are thinking or feeling. But it also affects your ability to understand written language related to emotions, according to research that was presented to the Society for Personal and Social Psychology in Las Vegas and that will be published in the journal Psychological Science.

The new study reported on 40 people who were treated with botulinum toxin, or Botox. Tiny applications of this powerful nerve poison were used to deactivate muscles in the forehead that cause frowning.

The interactions of facial expression, thoughts and emotions has intrigued scientists for more than a century, says the study's first author, University of Wisconsin-Madison psychology Ph.D. candidate David Havas.

Scientists have found that blocking the ability to move the body causes changes in cognition and emotion, but there were always questions. (One of the test treatments caused widespread, if temporary, paralysis.) In contrast, Havas was studying people after a pinpoint treatment to paralyze a single pair of "corrugator" muscles, which cause brow-wrinkling frowns.

To test how blocking a frown might affect comprehension of language related to emotions, Havas asked the patients to read written statements, before and then two weeks after the Botox treatment. The statements were angry ("The pushy telemarketer won't let you return to your dinner"), sad ("You open your e-mail in-box on your birthday to find no new e-mails") or happy ("The water park is refreshing on the hot summer day.").

Havas gauged the ability to understand these sentences according to how quickly the subject pressed a button to indicate they had finished reading it. "We periodically checked that the readers were understanding the sentences, not just pressing the button," says Havas.

The results showed no change in the time needed to understand the happy sentences. But after Botox treatment, the subjects took more time to read the angry and sad sentences. Although the time difference was small, it was significant, he adds. Moreover, the changes in reading time couldn't be attributed to changes in participants' mood.

The use of Botox to test how making facial expressions affect emotional centers in the brain was pioneered by Andreas Hennenlotter of the Max Planck Institute in Leipzig, Germany.

"There is a long-standing idea in psychology called the facial feedback hypothesis," says Havas. "Essentially, it says, when you're smiling, the whole world smiles with you. It's an old song, but it's right. Actually, this study suggests the opposite: When you're not frowning, the world seems less angry and less sad."

The Havas study broke new ground by linking the expression of emotion to the ability to understand language, says Havas' adviser, UW-Madison professor emeritus of psychology Arthur Glenberg. "Normally, the brain would be sending signals to the periphery to frown, and the extent of the frown would be sent back to the brain. But here, that loop is disrupted, and the intensity of the emotion and of our ability to understand it when embodied in language is disrupted."

Practically, the study "may have profound implications for the cosmetic-surgery," says Glenberg. "Even though it's a small effect, in conversation, people respond to fast, subtle cues about each other's understanding, intention and empathy. If you are slightly slower reacting as I tell you about something made me really angry, that could signal to me that you did not pick up my message."

Such an effect could snowball, Havas says, but the outcome could also be positive: "Maybe if I am not picking up sad, angry cues in the environment, that will make me happier."

In theoretical terms, the finding supports a psychological hypothesis called "embodied cognition," says Glenberg, now a professor of psychology at Arizona State University. "The idea of embodied cognition is that all our cognitive processes, even those that have been thought of as very abstract, are actually rooted in basic bodily processes of perception, action and emotion."

With some roots in evolutionary theory, the embodied cognition hypothesis suggests that our thought processes, like our emotions, are refined through evolution to support survival and reproduction.

Embodied cognition links two seemingly separate mental functions, Glenberg says. "It's been speculated at least since Darwin that the peripheral expression of emotion is a part of the emotion. An important role of emotion is social: It communicates 'I love you' or 'I hate you,' and it makes sense that there would be this very tight connection between peripheral expression and brain mechanism."

"Language has traditionally been seen as a very high-level, abstract process that is divorced from more primitive processes like action, perception and emotion," Havas says. "This study shows that far from being divorced from emotion, language understanding can be hindered when those peripheral bodily mechanism are interrupted."

University of Wisconsin

"PETER PAN" APES NEVER SEEM TO LEARN SELFISHNESS

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Sharing is a behavior on which day care workers and kindergarten teachers tend to offer young humans a lot of coaching. But for our ape cousins the bonobos, sharing just comes naturally.

In fact, according to a pair of papers in the latest Current Biology, it looks like bonobos never seem to learn how not to share. Chimpanzees, by contrast, are notorious for hogging food to themselves, by physical aggression if necessary. While chimps will share as youngsters, they grow out of it.

In several experiments to measure food-sharing and social inhibition among chimps and bonobos living in African sanctuaries, researchers from Duke and Harvard say these behavioral differences may be rooted in developmental patterns that portray something about the historical lifestyles of these two closely related apes.

When compared with chimps, bonobos seem to be living in "a sort of Peter Pan world," said Brian Hare, an assistant professor of evolutionary anthropology at Duke University, who participated in both studies. "They never grow up, and they share."

Hare and his mentor, Richard Wrangham, the Ruth Moore Professor of Anthropology at Harvard, think this kinder, gentler ape's behavior has been shaped by the relative abundance of their environment. Living south of the Congo River, where food is more plentiful, bonobos don't compete with gorillas for food as chimps have to, and they don't have to compete much with each other either.

In essence, they don't have to grow up, Hare said, and cognitive tests that the team performed on the captive animals seem to bear that out. Bonobos shared like juveniles even after they reached adulthood.

"It seems like some of these adult differences might actually derive from developmental differences," said Harvard graduate student Victoria Wobber, who is the lead author on one of the papers. "Evolution has been acting on the development of their cognition."

To measure sharing behavior, paired animals at the Tchimpounga Sanctuary in the Republic of the Congo were put into an enclosure with some food. Younger chimps were found to be quite similar to young bonobos in their willingness to share food, but the chimps become less willing to share when they're older.

In a second set of sharing experiments, Hare and a colleague at the Lola ya Bonobo sanctuary near Kinshasa, Democratic Republic of Congo gave bonobos an opportunity to have all of a food pile to themselves while a fellow bonobo watched helplessly from behind a gate. Instead, the subjects universally preferred to open the gate and let their friends share. Their friends weren't even begging or carrying on. (See YouTube video: http://www.youtube.com/watch?v=sRDc4SCaFLQ )

"A chimp would never voluntarily do that," Hare said. "Chimps will do things to help one another, but the one thing they will not do is share food."

In a series of tests on how socially savvy the apes were about asking others for handouts, the chimps were quick studies, but the bonobos never quite got the hang of it. In chimp society, where hogging the food pile is a privilege of rank, younger animals have to learn which adults can be begged from and which cannot, Wobber said.

In one test of social skills, Wobber had two humans hold treats concealed in their hands, while a third human was empty-handed. The animals were encouraged to ask for a treat by touching the hands. The chimps quickly picked up on the pattern and didn't bother begging from the empty-handed person. The bonobos were less discriminating and tried the empty hand just as much as the full ones.

A second social experiment used two people, one with a treat and one without. After the apes had it figured out, the treats were moved to the other human. The chimps caught on to the new pattern much more quickly than the bonobos.

These experiments don't mean the bonobos are less smart, Wobber said. It's just that they're less attuned to the social inhibitions a chimp would need to successfully share food without being slapped on the head.

The findings fit into a larger picture that Hare and Wrangham have been building in which animals that have been domesticated, such as pet dogs and arctic foxes in a long-term experiment in Siberia, possess what could be considered juvenile physical traits and behaviors, even after they've reached sexual maturity. It's an example, they say, of selection acting against aggression. Their behaviors are more juvenile, and so too are their physical features.

The research was funded by the National Science Foundation and the European Research Council.

(Photo: Vanessa Woods)

Duke University

EARLY HUMANS CAUSED EXTINCTION OF AUSTRALIA'S GIANT ANIMALS

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The mass extinction of Australia’s giant animals, such as huge kangaroos and rhinoceros-sized wombats, might have been more rapid than previously thought, according to new research from the University of Bristol. This suggests humans could have been responsible for wiping out the country’s megafauna between 50,000 and 40,000 years ago.

Working with researchers at the Australian National University (ANU) in Canberra, Dr Alistair Pike of Bristol’s Department of Archaeology and Anthropology analysed more than 60 megafauna bones and teeth found at Cuddie Springs in New South Wales.

Cuddie Springs is central to the debate about the timing and cause of the megafaunal extinctions as it is the only site known in continental Australia where human artefacts and megafauna remains have been found in the same sedimentary layers. These layers have previously been dated to between about 40,000 and 30,000 years ago leading to speculation it was climate change that wiped out the megafauna. However, the megafauna remains had not been dated directly – until now.

The researchers, led by Rainer Grün at the ANU, analysed the Cuddie Springs bones and teeth using uranium-series and electron spin resonance (ESR) dating techniques. Their results indicate that all the remains of the extinct species are at least 50,000 years old, and some are much older.

This suggests there was not a long period of coexistence between the giant animals and early humans, and that Australia’s megafauna could have been rapidly hunted to extinction during the period (60,000-45,000 years ago) when the first humans reached the continent.

Dr Pike said: “The cause of the disappearance of megafauna in Australia and also in Europe and North America is a hotly debated topic. Some researchers suggest it was climate change in the last ice age that caused their extinction, while others suggest it was overhunting by humans.

“The key to solving the problem is to develop methods to reliably date the bones of megafauna and compare them with the dates for the arrival of humans. In Bristol we have developed a method to date bones from the radioactive decay of the tiny amounts of uranium they contain. It is especially useful for sites like Cuddie Springs where older and younger material have become mixed through erosion.”

(Photo: Stanton F. Fink)

University of Bristol

ARTIFICIAL BEE SILK A BIG STEP CLOSER TO REALITY

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CSIRO scientist Dr Tara Sutherland and her team have achieved another important milestone in the international quest to artificially produce insect silk.

They have hand-drawn fine threads of honeybee silk from a ‘soup’ of silk proteins that they had produced transgenically.

These threads were as strong as threads drawn from the honeybee silk gland, a significant step towards development of coiled coil silk biomaterials.

“It means that we can now seriously consider the uses to which these biomimetic materials can be put,” Dr Sutherland said.

“We used recombinant cells of bacterium E. coli to produce the silk proteins which, under the right conditions, self-assembled into similar structures to those in honeybee silk.

“We already knew that honeybee silk fibres could be hand-drawn from the contents of the silk gland so used this knowledge to hand-draw fibres from a sufficiently concentrated and viscous mixture of the recombinant silk proteins.

“In fact, we had to draw them twice to produce a translucent stable fibre.”

Dr Sutherland said numerous efforts have been made to express other invertebrate silks in transgenic systems but the complicated structure of the silk genes in other organisms means that producing silk outside silk glands is very difficult.

“We had previously identified the honeybee silk genes and knew that that the silk was encoded by four small non-repetitive genes – a much simpler arrangement which made them excellent candidates for transgenic silk production.”

Possible practical uses for these silks would be tough, lightweight textiles, high-strength applications such as advanced composites for use in aviation and marine environments, and medical applications such as sutures, artificial tendons and ligaments.

(Photo: Nick Pitsas, CSIRO)

CSIRO

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